I'm new and learning Apex.  I'm having an issue with a trigger I wrote.  It hits the script statements govenor and causes the error "System.LimitException: Too many script statements: 200001".  It works with single updates. The error was caused when I tested it by updating 2,000 opportunity records and started after 937 were succesfully updated.

There are three revenue fields on Opportunity (Monthly, Prorated, Membership).  When an opportunity is updated, the trigger searchs through its products and determines which field the revenue belongs to using the product description.

trigger Test2 on Opportunity (before insert, before update) {

// CREATE PRODUCT LIST FOR THE OPPORTUNITIES
List<OpportunityLineItem> prodList = [select ID, OpportunityId, Description, TotalPrice from OpportunityLineItem where OpportunityId in: Trigger.new];

// DEFINE STRINGS USED TO DETERMINE TYPE OF PRODUCT
String Prorated = 'Prorated';
String Membership = 'Membership';

// LOOP THROUGH OPPORTUNITIES, RESET 3 REVENUE FIELDS TO 0
	for(Opportunity a : Trigger.new){
		a.Prorated_Total__c = 0;
		a.Membership_Total__c = 0;
		a.Monthly_Total__c = 0;

// LOOP THROUGH PRODUCT LIST TO GET REVENUE TYPE AND TOTAL FOR CURRENT OPPORTUNITY
		for(OpportunityLineItem b : prodList){

//  MAKE SURE PRODUCTS BELONG TO CURRENT OPPORTUNITY
			if(a.Id == b.OpportunityId){
// DETERMINES PRODUCT TYPE FROM DESCRIPTION AND ADDS PRICE TO THE CORRESPONDING FIELD ON THE CURRENT OPPORTUNITY
		    	     if(b.Description.contains(Prorated)){
		     	     a.Prorated_Total__c += b.TotalPrice;         
		   	     }else if(b.Description.contains (Membership)){        
			     a.Membership_Total__c += b.TotalPrice; 
		    	     }else{
		             a.Monthly_Total__c += b.TotalPrice;   
	    		     }
			}   
		}
	}
}

  After looking up the error, I'm sure the issue is with the nested loop. Everything else I tried failed and I'm struggling.  Any help is appreciated, thanks.